Package org.jcsp.util.ints
Class OverWritingBufferInt
java.lang.Object
org.jcsp.util.ints.OverWritingBufferInt
- All Implemented Interfaces:
Serializable
,Cloneable
,ChannelDataStoreInt
This is used to create a buffered integer channel that always accepts input,
overwriting its last entered data if full.
Description
OverWritingBufferInt is an implementation of ChannelDataStoreInt that yields a FIFO buffered semantics for a channel. When empty, the channel blocks readers. When full, a writer will overwrite the latest item written to the channel. See the static construction methods ofChannel
(Channel.one2oneInt(org.jcsp.util.ints.ChannelDataStoreInt)
etc.).
The getState method returns EMPTY or NONEMPTYFULL, but never FULL.
- See Also:
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final int[]
The storage for the buffered intsprivate int
The number of ints stored in the Bufferprivate int
The index of the oldest element (when counter > 0)private int
The index of the next free element (when counter invalid input: '<' buffer.length)private boolean
Fields inherited from interface org.jcsp.util.ints.ChannelDataStoreInt
EMPTY, FULL, NONEMPTYFULL
-
Constructor Summary
ConstructorsConstructorDescriptionOverWritingBufferInt
(int size) Construct a new OverWritingBufferInt with the specified size. -
Method Summary
Modifier and TypeMethodDescriptionclone()
Returns a new (and EMPTY) OverWritingBufferInt with the same creation parameters as this one.void
endGet()
SeestartGet()
for a description of the semantics of this method.int
get()
Returns the oldest int from the OverWritingBufferInt and removes it.int
getState()
Returns the current state of the OverWritingBufferInt.void
put
(int value) Puts a new int into the OverWritingBufferInt.void
int
startGet()
Begins an extended rendezvous by the reader.
-
Field Details
-
buffer
private final int[] bufferThe storage for the buffered ints -
counter
private int counterThe number of ints stored in the Buffer -
firstIndex
private int firstIndexThe index of the oldest element (when counter > 0) -
lastIndex
private int lastIndexThe index of the next free element (when counter invalid input: '<' buffer.length) -
valueWrittenWhileFull
private boolean valueWrittenWhileFull
-
-
Constructor Details
-
OverWritingBufferInt
public OverWritingBufferInt(int size) Construct a new OverWritingBufferInt with the specified size.- Parameters:
size
- the number of ints the OverWritingBufferInt can store.- Throws:
BufferIntSizeError
- if size is zero or negative. Note: no action should be taken to try/catch this exception - application code generating it is in error and needs correcting.
-
-
Method Details
-
get
public int get()Returns the oldest int from the OverWritingBufferInt and removes it.Pre-condition: getState must not currently return EMPTY.
- Specified by:
get
in interfaceChannelDataStoreInt
- Returns:
- the oldest int from the OverWritingBufferInt
-
startGet
public int startGet()Begins an extended rendezvous by the reader. The semantics of an extended rendezvous on an overwrite-newest buffer are slightly complicated, but hopefully intuitive. If the buffer is of size 2 or larger, the semantics are as follows. Beginning an extended rendezvous will return the oldest value in the buffer, but not remove it. If the writer writes to the buffer during the rendezvous, it will grow the buffer and end up overwriting the newest value as normal. At the end of the extended rendezvous, the oldest value is removed. If the buffer is of size 1, the semantics are identical to those of anOverWriteOldestBuffer
. For a complete description, refer to the documentation for theOverWriteOldestBuffer.startGet()
method.- Specified by:
startGet
in interfaceChannelDataStoreInt
- Returns:
- The oldest value in the buffer at this time
- See Also:
-
endGet
public void endGet()SeestartGet()
for a description of the semantics of this method.- Specified by:
endGet
in interfaceChannelDataStoreInt
- See Also:
-
put
public void put(int value) Puts a new int into the OverWritingBufferInt.If OverWritingBufferInt is full, the last item previously put into the buffer will be overwritten.
- Specified by:
put
in interfaceChannelDataStoreInt
- Parameters:
value
- the int to put into the OverWritingBufferInt
-
getState
public int getState()Returns the current state of the OverWritingBufferInt.- Specified by:
getState
in interfaceChannelDataStoreInt
- Returns:
- the current state of the OverWritingBufferInt (EMPTY or NONEMPTYFULL)
-
clone
Returns a new (and EMPTY) OverWritingBufferInt with the same creation parameters as this one.Note: Only the size and structure of the OverWritingBufferInt is cloned, not any stored data.
- Specified by:
clone
in interfaceChannelDataStoreInt
- Overrides:
clone
in classObject
- Returns:
- the cloned instance of this OverWritingBufferInt.
-
removeAll
public void removeAll()- Specified by:
removeAll
in interfaceChannelDataStoreInt
-